Added loopback address whitelisting override

LiteCharms.Features.MidrandBooks/Payments/Events/Handlers/PayfastPaymentConfirmationReceivedEventHandler.cs

@@ -61,7 +61,7 @@ public sealed class PayfastPaymentConfirmationReceivedEventHandler(IServiceProvi
 
         if (notification.PerformBackgroundChecks)
         {
-            var isHostValid = await payfastService.ValidateReferrerIpAsync(notification.RemoteIpAddress!, cancellationToken);
+            var isHostValid = await payfastService.ValidateReferrerIpAsync(notification.RemoteIpAddress!, notification.AllowLoopback, cancellationToken);
 
             if (isHostValid.IsFailed) 
                 throw new Exception("Security validation exception: Webhook packet source address failed cluster validation checks.");

LiteCharms.Features.MidrandBooks/Payments/Events/PayfastPaymentConfirmationReceivedEvent.cs

@@ -13,15 +13,18 @@ public sealed class PayfastPaymentConfirmationReceivedEvent : EventBase, IEvent
 
     public bool PerformBackgroundChecks { get; set; }
 
+    public bool AllowLoopback { get; set; }
+
     public PayfastPaymentConfirmationReceivedEvent() { }
 
-    private PayfastPaymentConfirmationReceivedEvent(PayfastWebhookPayload? payload, string paymentId, bool performBackgroundChecks = true)
+    private PayfastPaymentConfirmationReceivedEvent(PayfastWebhookPayload? payload, string paymentId, bool performBackgroundChecks = true, bool allowLoopback = false)
     {
         Payload = payload;
         CorrelationId = paymentId;
         PerformBackgroundChecks = performBackgroundChecks;
+        AllowLoopback = allowLoopback;
     }
 
-    public static PayfastPaymentConfirmationReceivedEvent Create(PayfastWebhookPayload? payload, string paymentId, bool performBackgroundChecks = true) =>
-        new(payload, paymentId, performBackgroundChecks);
+    public static PayfastPaymentConfirmationReceivedEvent Create(PayfastWebhookPayload? payload, string paymentId, bool performBackgroundChecks = true, bool allowLoopback = false) =>
+        new(payload, paymentId, performBackgroundChecks, allowLoopback);
 }

LiteCharms.Features.MidrandBooks/Payments/PayfastService.cs

@@ -49,7 +49,7 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
         }
     }
 
-    public async ValueTask<Result<bool>> ValidateReferrerIpAsync(string remoteIpAddress, CancellationToken cancellationToken = default)
+    public async ValueTask<Result<bool>> ValidateReferrerIpAsync(string remoteIpAddress, bool allowLoopback = false, CancellationToken cancellationToken = default)
     {
         if (string.IsNullOrWhiteSpace(remoteIpAddress)) 
             return Result.Fail<bool>("Remote IP address is null or whitespace.");
@@ -74,6 +74,12 @@ public sealed partial class PayfastService(IDbContextFactory<MidrandBooksDbConte
 
             if (IPAddress.TryParse(remoteIpAddress, out var incomingIp))
             {
+                if (allowLoopback && IPAddress.IsLoopback(incomingIp))
+                {
+                    logger.LogInformation("Local development loopback IP '{RemoteIp}' allowed bypassing DNS verification.", remoteIpAddress);
+                    return Result.Ok(true);
+                }
+
                 bool isValid = validIps.Contains(incomingIp);
 
                 if (!isValid)